Electronic devices composed of organic-based transistors can be manufactured at lower cost and applied to a larger area format than their inorganic counterparts albeit with reduced performance. In general, organic-based transistors utilize either small molecules or polymers as the semiconductor material. Typically, small molecule semiconductor materials have low solubility in organic solvents and thus require a vacuum deposition method to form films. Shadow mask or photolithographic methods are required to pattern multiple layers in order to make useful devices. Vacuum deposition and lithography require processes that cost much more than processes that do not require vacuum deposition and lithography (e.g., solution coating methods).
One cost effective approach of producing inexpensive electronic devices is to apply an organic semiconductor material by any of the following exemplary coating processes: spin coating, knife-coating, roll-to-roll web-coating, and dip coating, as well as printing processes such as ink-jet printing, screen printing, and offset lithography. However, as discussed above, organic semiconductor materials are notoriously insoluble in solvents and those that are soluble are generally unstable in solution. Due to insolubility and instability concerns, the ability to apply organic semiconductor materials using the above-mentioned inexpensive coating steps to form inexpensive electronic devices is limited.
Some organic semiconductors based on pentacene with 6,13-silylethynyl substitution have been shown to (i) be soluble in organic solvents, (ii) be stable in solution, and (iii) provide good performance in organic field effect transistors (OFETs). For example, 6,13-bis[(triisopropylsilyl)ethynyl]pentacene (i.e., also referred to herein as “TIPS-pentacene”) has been shown to (i) have a degree of solubility in organic solvents, (ii) have a degree of stability when in solution, and (iii) provide good performance in organic field effect transistors (OFETs). However, even TIPS-pentacene provides limited solubility in some organic solvents, as well as limited performance in electronic devices (e.g., transistors), for example, as measured in terms of charge carrier mobility values.